Such gas springs are widely used, among other uses, as lifting devices for hatchbacks or trunk lids of motor vehicles. Usually the dimensioning and installation of the gas springs is such that their outward-pushing force is exactly sufficient to raise the trunk lid or hatchback to the uppermost open position, so that a corresponding oppositely directed force must be applied to close the hatchback or trunk lid.
The following problems can arise in this connection. If a vehicle is to be operated with the hatchback in the open position, for example, with objects being transported protruding out of the cargo space, or if the vehicle is to be operated only for short stretches between individual loading and unloading procedures, the hatchback will vibrate in its uppermost raised position, since it is supported by a spring. Gas springs are filled with compressed gas at a room temperature of approximately 20.degree. C. When the outside temperature falls, the gas pressure in the gas spring decreases, so that at relatively very low ambient temperatures this can result in the outward-pushing force of the spring no longer being sufficient to raise the hatchback or the trunk lid and, what is still more important, to keep such hatchback or lid in its uppermost open position. For example, it should be pointed out that the gas pressure in the gas springs filled at +20.degree. C decreases about 20 percent at a temperature of -40.degree. C.
Finally, a gas spring may have slight leaks in it, so that until the gas spring is replaced by a new one, the hatchback or trunk lid will not stay in its uppermost position. In order to avoid these problems, supporting hinges are often provided between the fixed and swinging parts of the hatchback or trunk lid, to supplement the gas spring, the supporting hinges holding the swinging part in the raised position and allowing it to swing down again only when a rigidly interlocking latch on the two arms of such a hinge is released.